Digital versatile discs (DVDs) are information storage devices used for storing prerecorded audio information, movies and computer software. The storage and playback mechanism used in DVDs closely resembles the mechanism used in compact discs (CDS), DVD players and software use the same laser technology as CD players. Briefly, both DVDs and CDS store information as a pattern of pits formed in a metallic substrate. The pit patterns form digital words and can be read by shining a laser beam on the disc surface and detecting the reflected beam. However, the information storage capacity of a typical DVD is much higher than a CD. Presently available DVDs have a variety of capacities which depend on the technology used to manufacture the discs. Single-layer technologies can be either single or double-sided with capacities of 4.7 gigabytes and 9.4 gigabytes, respectively. Dual layer technologies are available which use single or double sided capacities that hold approximately 8.5 gigabytes per side. This high information storage capacity makes DVDs suitable for storing not only audio information, but also video information and large amounts of computer data as well.
DVD players have many CD player features, such as the ability to play selections in any order desired and the ability to read information from any point on the disc. However, DVDs can store information in several formats. For example, DVDs which are used to store video information (hereinafter called DVD-VIDEO discs) may use various known information compression algorithms, such as MPEG-2 for video compression/decompression. A DVD may also include high fidelity sound as well. In addition, a DVD may also store uncompressed linear pulse code modulated data streams which have sample rates between 48-90 kHertz and are sampled at 16 or 24 bits. Still other DVD versions (hereinafter called DVD-ROM discs) can store digital data for computer use, and the data may also be compressed on these discs.
Although DVD-ROM and DVD-VIDEO discs share compression algorithms, the data format on DVD-VIDEO discs is significantly different than the data format found on DVD-ROM discs. One important difference is that the data content on DVD-ROM is platform-specific, while DVD-VIDEO discs operate with a platform independent navigation engine for playing interactive movies. This navigation engine requires that the files on the DVD.sub.-- VIDEO disc be referenced in predetermined directory structure.
In particular, each DVD-VIDEO disc contains a main directory denoted as a VIDEO.sub.-- TS directory which contains two types of files distinguished with the file extensions .IFO and .VOB. During playback, these files are sorted by a DVD video player to form video "title" sets, which are groupings of all files necessary to play a particular DVD video "title", for example, a movie. Each video title set is composed of one .IFO file and one or more .VOB files.
A file with the .VOB extension contains the actual multimedia data and is called a video object set. The location and format of the multimedia data stored in the video object set is defined by the associated .IFO file. In particular, .IFO files contain navigational data structures and a processor-independent interpreted language which specifies how the data structures are arranged.
The data structures themselves are composed of various objects called "program chain objects", "program objects", and "cell objects". Program chain objects link related program objects (or particular scenes) within a title and their data structures govern the playback of the program objects. For example, a simple title may contain only one program chain. However, complex titles may contain two or more program chains to allow random access to a variety of programs. The multiple program chain title can play programs linearly, randomly or in a "shuffle" mode. Program chains allow a particular program sequence to be changed during playback. Thus, it is possible to change the program contact based on stored information. This type of operation is used in implementing "parental control" levels in which information content which parents might find inappropriate (such as extremely violent or sexual material) can be removed from a playback and other material substituted without requiring several separate and complete programs.
Each program object in a program chain is composed of elements called "cell objects". These objects instruct a DVD player which portion of the multimedia data in one of the .VOB files to decode. In particular, the data structures in a cell object are defined in the .IFO file and the multimedia content is found in one of the .VOB files. Each cell object directs the DVD player to begin playback at a specific location in the .VOB file which is referred to as a video object unit or "VOBU". A VOBU is a container object that includes both multimedia data and playback program commands. More specifically, each VOBU may contain a header or navigation pack called an "NV.sub.-- PACK" that, in turn, contains navigational commands, user operation data and "highlight" commands which control the presentation of the information on the display.
The specific program commands which are recognized by a DVD player are controlled by a device independent language and a set of DVD player parameters which define the current state of the DVD player. These commands cause the DVD player to perform a number of operations, such as generating menu controls at specific locations on the display screen. In order to process these commands a DVD player system typically includes a processor and associated memory (which may be part of the player or a separate computer) and display device. Preferably, the player system is controlled by a playback program running under an operating system such as WINDOWS NT.RTM. or OS/2.RTM..
Input can also be obtained directly from a user by means of displayed controls, such as buttons, which can be displayed under playback program control on screen along with the multimedia data in an arrangement called a graphic user interface. The playback program controls both the time duration that a control appears on the screen and the manner that the system responds to the selection of a control by a user. For example, user selection of a button may cause the playback program to jump to a new location on the disk and begin playback at the new location. The playback program may also display menus which guide a user through various tasks.
However, in prior art systems the graphic user interface was fixed and therefore had the same appearance no matter what multimedia data was being displayed. In some cases, the menu selection and controls were inappropriate for the information content actually displayed. Further, user interfaces tended to be generic because they had to service many different types of data. Accordingly, in other cases, selective controls which would have made the system much easier to use were simply not available on the generic interfaces.
Other prior art systems generated a graphic user interface including controls generated on the navigation commands in the DVD data stream, but these devices merely displayed controls at locations specified by the navigation data and were thus limited in the construction of screen displays to the sparse data in the DVD data stream.
Accordingly, it would be desirable to have a DVD system that ensures appropriate user interfaces which are customized based upon the DVD information content to allow efficient and easily understandable manipulation of the DVD player and data.
It would be further desirable to construct a graphic user interface based not only on navigational data, but also other information to create a dynamic display.